Title: Polyethylenimine coated agarose supports, for the reversible immobilisation of β-galactosidase from Aspergillus oryzae

Authors: Paula Gonzalez, Francisco Batista-Viera, Beatriz M. Brena

Addresses: Catedra de Bioquimica, Facultad de Quimica, General Flores 2124, CC 1157 Montevideo, Uruguay. ' Catedra de Bioquimica, Facultad de Quimica, General Flores 2124, CC 1157 Montevideo, Uruguay. ' Catedra de Bioquimica, Facultad de Quimica, General Flores 2124, CC 1157 Montevideo, Uruguay

Abstract: Immobilised enzymes for industrial applications should be very active and operationally stable. Reversible binding, if possible, is desirable to allow matrix reuse. Usually these aims come into conflict: strong binding may imply low expressed activity and poor reversibility. Immobilisation of Aspergillus oryzae β-galactosidase to conventional ionic exchangers is efficient but the derivatives exhibit noticeable enzyme leakage when used for the hydrolysis of lactose from whey. This problem can be avoided by covalent cross-links to the matrix, at the expense of losing reversibility. We have optimised the conditions for polyethylenimine (PEI)-coating of agarose supports to achieve a β-galactosidase derivative that allows a high lactose conversion from whey in a steady bed-reactor with no enzyme leakage, together with good elution properties. Therefore, PEI-coating appears to be a very suitable strategy to convert the agarose surface to an adequate support for a reversible, but strong and non-distorting, ionic protein immobilisation.

Keywords: β-galactosidase; ionic immobilisation; polyethylenimine supports; reversible immobilisation; Aspergillus oryzae; high lactose conversion; whey; PEI coating.

DOI: 10.1504/IJBT.2004.005504

International Journal of Biotechnology, 2004 Vol.6 No.4, pp.338 - 345

Published online: 12 Oct 2004 *

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